Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, at least four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and a brake actuatable in combinations of three to establish a plurality of forward gear ratios and at least one reverse gear ratio.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/722,480 filed Nov. 5, 2012. The disclosure of the above applicationis incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission, andmore particularly, to a transmission having a plurality speeds, fourplanetary gear sets and a plurality of torque transmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness, and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member, atleast four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices may be, for example, clutches and a brake.

The clutches and brake can be of any type including but not limited to afiction clutch, a friction band, a one way clutch, a selectable one wayclutch, a dog clutch, a synchronizer and similar devices. Furthermore,any node can use a single device or a combination of these devices e.g.the brake may be configured as a dog clutch and a one way clutchcombination or a one way clutch and friction clutch combination.Similarly, several other combinations are possible.

In another embodiment of the present invention, the transmissionincludes: first, second, third and fourth planetary gear sets eachhaving a sun gear, a carrier member and a ring gear, and the inputmember is continuously connected for common rotation with the carriermember of the third planetary gear set, and the output member iscontinuously connected for common rotation with the carrier member ofthe fourth planetary gear set.

In yet another embodiment of the present invention, the transmissionincludes a first interconnecting member that continuously interconnectsthe carrier member of the first planetary gear set with the sun gear ofthe second planetary gear set and the ring gear of the third planetarygear set.

In yet another embodiment of the present invention, the transmissionincludes a second interconnecting member that continuously interconnectsthe carrier member of the second planetary gear set with the carriermember of the fourth planetary gear set.

In yet another embodiment of the present invention, the transmissionincludes a third interconnecting member that continuously interconnectsthe sun gear of the third planetary gear set is permanently coupled tothe sun gear of the fourth planetary gear set.

In yet another embodiment of the present invention, the transmissionincludes a grounding member for continuously interconnecting the sungear of the first planetary gear set to a stationary member.

In still another embodiment of the present invention, the transmissionincludes a first torque transmitting mechanism that is selectivelyengageable to interconnect the carrier member of the third planetarygear set and the input member with a common structural member.

In still another embodiment of the present invention, the transmissionincludes a second torque transmitting mechanism that is selectivelyengageable to interconnect the ring gear of the second planetary gearset with the common structural member.

In still another embodiment of the present invention, the transmissionincludes a third torque transmitting mechanism that is selectivelyengageable to interconnect the sun gear of the third planetary gear setand the sun gear of the fourth planetary gear set with the commonstructural member.

In still another embodiment of the present invention, the transmissionincludes a fourth torque transmitting mechanism that is selectivelyengageable to interconnect the ring gear of the first planetary gear setwith the common structural member.

In still another embodiment of the present invention, the transmissionincludes a fifth torque transmitting mechanism that is selectivelyengageable to interconnect the ring gear of the first planetary gear setwith the carrier member of the second planetary gear set, the carriermember of the fourth planetary gear set and the output member.

In still another embodiment of the present invention, the transmissionincludes a sixth torque transmitting mechanism that is selectivelyengageable to interconnect the ring gear of the fourth planetary gearset with the stationary member.

In yet another embodiment of the present invention, the torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish a plurality of forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.

Further features, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a transmission accordingto the principles of present invention;

FIG. 2 is a diagrammatic illustration of a variation of the transmissionof FIG. 1 according to the principles of the present invention; and

FIG. 3 is a truth table presenting an example of a state of engagementof various torque transmitting elements to produce multiple forward andat least one reverse speed or gear ratios of the transmissionsillustrated in FIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that the embodiments of themulti-speed automatic transmission of the present invention have anarrangement of permanent mechanical connections between the elements ofthe four planetary gear sets. As used herein, coupling orinterconnection refers to a direct, continuous, and permanent couplingor interconnection, for example by a rigid member or shaft, betweenelements. Selective coupling or interconnection, on the other hand,refers to a selective coupling by a clutch or brake, where the clutch orbrake can be engaged and disengaged, such that when engaged, theselectively coupled or interconnected elements rotate together, but whendisengaged, the selectively coupled or interconnected elements are freeto rotate independently.

In one embodiment, a second component or element of the first planetarygear set is permanently coupled to a third component or element of thesecond planetary gear set and a third component or element of the thirdplanetary gear set. A second component or element of the secondplanetary gear set is permanently coupled to a second component orelement of the fourth planetary gear set. A first component or elementof the third planetary gear set is permanently coupled to a firstcomponent or element of the fourth planetary gear set.

Referring now to FIG. 1, an embodiment of a multi-speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear are each represented by a node. Therefore, a single lever containsthree nodes: one for the sun gear, one for the planet gear carrier, andone for the ring gear. The relative length between the nodes of eachlever can be used to represent the ring-to-sun ratio of each respectivegear set. These lever ratios, in turn, are used to vary the gear ratiosof the transmission in order to achieve an appropriate ratios and ratioprogression. Mechanical couplings or interconnections between the nodesof the various planetary gear sets are illustrated by thin, horizontallines, and torque transmitting devices such as clutches and brakes arepresented as interleaved fingers. Further explanation of the format,purpose and use of lever diagrams can be found in SAE Paper 810102, “TheLever Analogy: A New Tool in Transmission Analysis” by Benford andLeising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14, a second planetary gear set 16, a third planetarygear set 18, a fourth planetary gear set 20, and an output shaft ormember 22. In the lever diagram of FIG. 1, the first planetary gear set14 has three nodes: a first node 14A, a second node 14B, and a thirdnode 14C. The second planetary gear set 16 has three nodes: a first node16A, a second node 16B and a third node 16C. The third planetary gearset 18 has three nodes: a first node 18A, a second node 18B and a thirdnode 18C. The fourth planetary gear set 20 has three nodes: a first node20A, a second node 20B and a third node 20C. The input member 12 iscontinuously coupled to the second node 18B of the third planetary gearset 18. The output member 22 is continuously coupled to the second node20B of the fourth planetary gear set 20.

The second node 14B of the first planetary gear set 14 is coupled to thethird node 16C of the second planetary gear set 16 and to the third node18C of the third planetary gear set 18. The third node 14C of the firstplanetary gear set 14 is coupled to a stationary member or atransmission housing 50. The second node 16B of the second planetarygear set 16 is coupled to the second node 20B of the fourth planetarygear set 20. The first node 18A of the third planetary gear set 18 iscoupled to the first node 20A of the fourth planetary gear set 20.

Transmission 10 has a plurality of torque transmitting mechanisms, suchas clutches and brakes, which transfer torque from one node or elementof the planetary gear sets to another. Moreover, transmission 10includes a common node J. Common node J is a structural member thatinterconnects a number of the torque transmitting mechanisms, asdescribed hereinafter.

For example, a first clutch 24 selectively connects the second node 18Bof the third planetary gear set 18 with the common node J. A secondclutch 26 selectively connects the first node 16A of the secondplanetary gear set 16 with the common node J. A third clutch 28selectively connects the first node 18A of the third planetary gear set18 and the first node 20A of the fourth planetary gear set 20 with thecommon node J. A fourth clutch 30 selectively connects the first node14A of the first planetary gear set 14 with the common node J. A fifthclutch 32 selectively connects the second node 16B of the secondplanetary gear set 16 and the second node 20B of the fourth planetarygear set 20 with the first node 14A of the first planetary gear set 14.A brake 34 selectively connects the third node 20C of the firstplanetary gear set 20 with the stationary member or transmission housing50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofan embodiment of the multi-speed transmission 10 according to one formof the present invention. In FIG. 2, the numbering from the leverdiagram of FIG. 1 is carried over. The clutches and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, the first planetary gear set 14 includes a sun gear member14C, a ring gear member 14A and a planet gear carrier member 14B thatrotatably supports a set of planet gears 14D (only one of which isshown). The sun gear member 14C is connected with a first shaft orinterconnecting member 42. The first shaft or interconnecting member 42fixedly connects sun gear member 14C to the transmission housing 50. Thering gear member 14A is connected for common rotation with a secondshaft or interconnecting member 44. The planet carrier member 14B isconnected for common rotation with third shaft or interconnecting member46 and a fourth shaft or interconnecting member 48. The set of planetgears 14D are each configured to intermesh with both the sun gear member14A and the ring gear member 14C.

The second planetary gear set 16 includes a sun gear member 16C, a ringgear member 16A and a planet gear carrier member 16B that rotatablysupports a set of planetary gears 16D (only one of each is shown). Thesun gear member 16C is connected for common rotation with the fourthshaft or interconnecting member 48. The ring gear member 16A isconnected directly to the second clutch 26. The planet carrier member16B is connected for common rotation with a fifth shaft orinterconnecting member 52 and the sixth shaft or interconnecting member54. The planet gears 16D are each configured to intermesh with both thering gear member 16A and the sun gear member 16C.

The third planetary gear set 18 includes a sun gear member 18A, a ringgear member 18C and a planet gear carrier member 18B that rotatablysupports a set of planet gears 18D (only one of which is shown). The sungear member 18A is connected for common rotation with a seventh shaft orinterconnecting member 56. The ring gear member 18C is connected forcommon rotation with the third shaft or interconnecting member 46. Theplanet carrier member 18B is connected for common rotation with theinput shaft or member 12 and an eighth shaft or interconnecting member58. The planet gears 18D are each configured to intermesh with both thesun gear member 18A and the ring gear member 18C.

The fourth planetary gear set 20 includes a sun gear member 20A, a ringgear member 20C and a planet gear carrier member 20B that rotatablysupports a set of planet gears 20D (only one of which is shown). The sungear member 20A is connected for common rotation with a seventh shaft orinterconnecting member 56. The ring gear member 20C is connecteddirectly to the brake 34. The planetary gear carrier member 20B isconnected for common rotation with the output shaft or member 22 andwith the fifth shaft or interconnecting member 52. The planet gears 20Dare each configured to intermesh with both the sun gear member 20A andthe ring gear member 20C.

The input shaft or member 12 is continuously connected to an inputsource, such as an engine (not shown) or a turbine of a torque converter(not shown). The output shaft or member 22 is continuously connectedwith another output such as the final drive unit or transfer case (notshown).

The torque-transmitting mechanisms, including the first, second, third,fourth and fifth clutches 24, 26, 28, 30, 32 and the brake 34 allow forselective interconnection of the shafts or interconnecting members 42,44, 46, 48, 52, 54, 56 and 58 of the planetary gear sets 14, 16, 18, 20and the housing 50.

For example, the first clutch 24 is selectively engageable to connectthe eighth shaft or interconnecting member 58 with the common member orhub J. The second clutch 26 is selectively engageable to connect thering gear 16A of the second planetary gear set 16 with the common memberor hub J. The third clutch 28 is selectively engageable to connect theseventh shaft or interconnecting member 56 with the common member or hubJ. The fourth clutch 30 is selectively engageable to connect the secondshaft or interconnecting member 44 with the common member or hub J. Thefifth clutch 32 is selectively engageable to connect the second shaft orinterconnecting member 44 with the sixth shaft or interconnecting member54. The brake 34 is selectively engageable to connect the ring gear 20Cof the fourth planetary gear set 20 with the stationary element or thetransmission housing 50 in order to restrict the ring gear 20C fromrotating relative to the transmission housing 50. In turn, thecomponents of the planetary gear sets connected to each of theconnecting members are also connected or restricted accordingly.

Referring now to FIGS. 1, 2 and 3, the operation of the multi-speedtransmission 10 will be described. It will be appreciated thattransmission 10 is capable of transmitting torque from the input shaftor member 12 to the output shaft or member 22 in multiple forward speedtorque ratios and at least one reverse speed or torque ratio. Eachforward and reverse speed or torque ratio is attained by engagement ofone or more of the torque-transmitting mechanisms (i.e. first clutch 24,second clutch 26, third clutch 28, fourth clutch 30, fifth clutch 32 andbrake 34), as will be explained below.

FIG. 3 is a truth table presenting the various combinations oftorque-transmitting mechanisms that are activated or engaged to achievethe various gear states. An “X” in the box means that the particularclutch or brake is engaged to achieve the desired gear state. Actualnumerical gear ratios of the various gear states are also presentedalthough it should be appreciated that these numerical values areexemplary only and that they may be adjusted over significant ranges toaccommodate various applications and operational criteria of thetransmission 10. Of course, other gear ratios are achievable dependingon the gear diameter, gear teeth count and gear configuration selected.

For example, a reverse gear is established by engaging or activating thesecond clutch 26, the third clutch 28 and the brake 34. The secondclutch 26 connects the ring gear 16A of the second planetary gear set 16with the common member or hub J. The third clutch 28 connects theseventh shaft or interconnecting member 56 with the common member or hubJ. The brake 34 connects the ring gear 20C of the fourth planetary gearset 20 with the stationary element or the transmission housing 50 inorder to restrict the ring gear 20C from rotating relative to thetransmission housing 50. Likewise, the eleven forward ratios areachieved through different combinations of clutch and brake engagement,as shown in FIG. 3, by way of example.

It will be appreciated that the foregoing explanation of operation andgear states of the multi-speed embodiment of transmission 10 assumes,first of all, that all the clutches not specifically referenced in agiven gear state are inactive or disengaged and, second of all, thatduring gear shifts, i.e., changes of gear state, between at leastadjacent gear states, a clutch engaged or activated in both gear stateswill remain engaged or activated. Further, the operation andestablishment of various gear ratios of transmission 10 are for exampleprovided by the engagement of the torque transmitting elements, as shownin FIG. 3.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; three interconnecting members continuouslyinterconnecting a member of the first, second, third and fourthplanetary gear sets with another member of the first, second, third andfourth planetary gear sets; a grounding member for continuouslyinterconnecting at least one of the members of the planetary gear setsto a stationary member; and six torque transmitting mechanisms whereinfive of the six torque transmitting mechanisms are each selectivelyengageable to interconnect at least one of the first, second and thirdmembers with at least one other of the first, second, third members anda common structural member and wherein one of the six torquetransmitting mechanisms are each selectively engageable to interconnectat least one of the first, second and third members with the stationarymember, and wherein the six torque transmitting mechanisms areselectively engageable in combinations of at least three to establish aplurality of forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 2. The transmission ofclaim 1 wherein the three interconnecting members further comprises afirst interconnecting member continuously interconnecting a secondmember of the first planetary gear set with a third member of the secondplanetary gear set and a third member of the third planetary gear set, asecond interconnecting member continuously interconnecting a secondmember of the second planetary gear set with a second member of thefourth planetary gear set and a third interconnecting membercontinuously interconnecting a first member of the third planetary gearset is permanently coupled to a first member of the fourth planetarygear set.
 3. The transmission of claim 1 wherein the grounding memberinterconnects the third member of the first planetary gear set to thestationary member.
 4. The transmission of claim 1 wherein a first of thesix torque transmitting mechanisms is selectively engageable tointerconnect the second member of the third planetary gear set and theinput member with the common structural member.
 5. The transmission ofclaim 4 wherein a second of the six torque transmitting mechanisms isselectively engageable to interconnect the first member of the secondplanetary gear set with the common structural member.
 6. Thetransmission of claim 5 wherein a third of the six torque transmittingmechanisms is selectively engageable to interconnect the first member ofthe third planetary gear set and the first member of the fourthplanetary gear set with the common structural member.
 7. Thetransmission of claim 6 wherein a fourth of the six torque transmittingmechanisms is selectively engageable to interconnect the first member ofthe first planetary gear set with the common structural member.
 8. Thetransmission of claim 7 wherein a fifth of the six torque transmittingmechanisms is selectively engageable to interconnect the first member ofthe first planetary gear set with the second member of the secondplanetary gear set, the second member of the fourth planetary gear setand the output member.
 9. The transmission of claim 8 wherein a sixth ofthe six torque transmitting mechanisms is selectively engageable tointerconnect the third member of the fourth planetary gear set with thestationary member.
 10. The transmission of claim 1 wherein the inputmember is continuously connected for common rotation with the secondmember of the third planetary gear set and the output member iscontinuously connected for common rotation with the second member of thefourth planetary gear set.
 11. The transmission of claim 1 wherein thethird member of the first planetary gear set, the third member of thesecond planetary gear set, the first member of the third planetary gearset and the first member of the fourth planetary gear set are sun gears,the second members of the first, second, third and fourth planetary gearsets are carrier members and the first member of the first planetarygear set, the first member of the second planetary gear set, the thirdmember of the third planetary gear set and the third member of thefourth planetary gear set are ring gears.
 12. A transmission comprising:an input member; an output member; first, second, third and fourthplanetary gear sets each having first, second and third members; a firstinterconnecting member continuously interconnecting a second member ofthe first planetary gear set with a third member of the second planetarygear set and a third member of the third planetary gear set; a secondinterconnecting member continuously interconnecting a second member ofthe second planetary gear set with a second member of the fourthplanetary gear set; a grounding member for continuously interconnectingat least one of the members of the planetary gear sets to a stationarymember; a third interconnecting member continuously interconnecting afirst member of the third planetary gear set is permanently coupled to afirst member of the fourth planetary gear set; and six torquetransmitting mechanisms each selectively engageable to interconnect atleast one of the first, second, and third members with at least oneother of the first, second, third members and a common structural memberand the stationary member, and wherein the six torque transmittingmechanisms are selectively engageable in combinations of at least threeto establish a plurality of forward speed ratios and at least onereverse speed ratio between the input member and the output member. 13.The transmission of claim 12 wherein a first of the six torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the third planetary gear set and the input member withthe common structural member
 14. The transmission of claim 13 wherein asecond of the six torque transmitting mechanisms is selectivelyengageable to interconnect the first member of the second planetary gearset with the common structural member.
 15. The transmission of claim 14wherein a third of the six torque transmitting mechanisms is selectivelyengageable to interconnect the first member of the third planetary gearset and the first member of the fourth planetary gear set with thecommon structural member.
 16. The transmission of claim 15 wherein afourth of the six torque transmitting mechanisms is selectivelyengageable to interconnect the first member of the first planetary gearset with the common structural member.
 17. The transmission of claim 16wherein a fifth of the six torque transmitting mechanisms is selectivelyengageable to interconnect the first member of the first planetary gearset with the second member of the second planetary gear set, the secondmember of the fourth planetary gear set and the output member.
 18. Thetransmission of claim 17 wherein a sixth of the six torque transmittingmechanisms is selectively engageable to interconnect the third member ofthe fourth planetary gear set with the stationary member.
 19. Thetransmission of claim 12 wherein the grounding member interconnects thethird member of the first planetary gear set to the stationary member.20. The transmission of claim 12 wherein the input member iscontinuously connected for common rotation with the second member of thethird planetary gear set and the output member is continuously connectedfor common rotation with the second member of the fourth planetary gearset.
 21. The transmission of claim 12 wherein the third member of thefirst planetary gear set, the third member of the second planetary gearset, the first member of the third planetary gear set and the firstmember of the fourth planetary gear set are sun gears, the secondmembers of the first, second, third and fourth planetary gear sets arecarrier members and the first member of the first planetary gear set,the first member of the second planetary gear set, the third member ofthe third planetary gear set and the third member of the fourthplanetary gear set are ring gears.
 22. A transmission comprising: aninput member; an output member; first, second, third and fourthplanetary gear sets each having a sun gear, a carrier member and a ringgear, wherein the input member is continuously connected for commonrotation with the carrier member of the third planetary gear set, andwherein the output member is continuously connected for common rotationwith the carrier member of the fourth planetary gear set; a firstinterconnecting member continuously interconnecting the carrier memberof the first planetary gear set with the sun gear of the secondplanetary gear set and the ring gear of the third planetary gear set; asecond interconnecting member continuously interconnecting the carriermember of the second planetary gear set with the carrier member of thefourth planetary gear set; a third interconnecting member continuouslyinterconnecting the sun gear of the third planetary gear set ispermanently coupled to the sun gear of the fourth planetary gear set; agrounding member for continuously interconnecting the sun gear of thefirst planetary gear set to a stationary member; a first torquetransmitting mechanism selectively engageable to interconnect thecarrier member of the third planetary gear set and the input member witha common structural member; a second torque transmitting mechanismselectively engageable to interconnect the ring gear of the secondplanetary gear set with the common structural member; a third torquetransmitting mechanism selectively engageable to interconnect the sungear of the third planetary gear set and the sun gear of the fourthplanetary gear set with the common structural member; a fourth torquetransmitting mechanism selectively engageable to interconnect the ringgear of the first planetary gear set with the common structural member;a fifth torque transmitting mechanism selectively engageable tointerconnect the ring gear of the first planetary gear set with thecarrier member of the second planetary gear set, the carrier member ofthe fourth planetary gear set and the output member; and a sixth torquetransmitting mechanism selectively engageable to interconnect the ringgear of the fourth planetary gear set with the stationary member, andwherein the torque transmitting mechanisms are selectively engageable incombinations of at least three to establish a plurality of forward speedratios and at least one reverse speed ratio between the input member andthe output member.